Mobilization of glucose from the liver during exercise and replenishment afterward.

The liver is anatomically well situated to regulate blood glucose. It is positioned downstream from the pancreas, which releases the key regulatory hormones glucagon and insulin. It is also just downstream from the gut, permitting efficient extraction of ingested glucose and preventing large excursions in systemic glucose after a glucose-rich meal. The position of the liver is not as well situated from the standpoint of experimentation and clinical assessment, as its primary blood supply is impossible to access in conscious human subjects. Over the last 20 years, to study hepatic glucose metabolism during and after exercise, we have utilized a conscious dog model which permits sampling of the blood that perfuses (portal vein, artery) and drains (hepatic vein) the liver. Our work has demonstrated the key role of exercise-induced changes in glucagon and insulin in stimulating hepatic glycogenolysis and gluconeogenesis during exercise. Recently we showed that portal venous infusion of the pharmacological agent 5'-aminoimidazole-4-carboxamide-1-beta-D-ribofuranoside leads to a marked increase in hepatic glucose production. Based on this, we propose that the concentration of AMP may be a component of a physiological pathway for stimulating hepatic glucose production during exercise. Insulin-stimulated hepatic glucose uptake is increased following exercise by an undefined mechanism that is independent of liver glycogen content. The fate of glucose taken up by the liver is critically dependent on hepatic glycogen stores, however, as glycogen deposition is greatly facilitated by prior glycogen depletion.     

Blue toe syndrome: treatment with percutaneous atherectomy

"Blue toe syndrome" refers to digital ischemia of the foot in the presence of palpable or Doppler audible pedal pulses. This clinical syndrome is caused by microembolization to small vessels from a proximal source. The use of percutaneous transluminal atherectomy is described in the treatment of embologenic superficial femoral artery lesions in seven patients. All seven had prompt healing of the ischemic toes, and none required surgical revascularization or amputation. One patient developed a recurrent stenosis at the atherectomy site and had a second episode of digital ischemia, which was treated by means of atherectomy with a larger device. Histologic study of atherectomy specimens suggests that emboli arise from adherent fibrinoplatelet aggregates or thrombus and less often from cholesterol-rich atheromatous plaque. Although either percutaneous transluminal angioplasty or atherectomy can be used to treat the underlying stenosis, percutaneous atherectomy offers the advantage of nonsurgical removal of embologenic material and provides material for histologic study. Percutaneous atherectomy is an effective method of treating embologenic superficial femoral stenoses in patients with ipsilateral blue toe syndrome.     

A Top–Down and Bottom–Up Component of Visual Attention

A new constituent of visual attention theory is proposed based on research in an animal model system. That showed that the neuromodulators released by efference from that animal’s brain can accelerate or retard the potentials produced by visual stimulation of that animal’s photoreceptors. Such a possibility has never been considered in human behavioral research even though it has been clearly demonstrated that attention can alter the temporal window of visual perception. We therefore propose that attention theory should include new top–down and bottom–up components (TBC) with a top–down component that involves efferents that go from the brain to the photoreceptors and a bottom–up component that involves consequent neuromodulatory alterations of the timing of the afferent photoreceptor potentials evoked by light stimuli. Not long ago, it would have been infeasible to test the validity of TBC in humans. However, newly developed multifocal electroretinogram (mfERG) technology makes it possible to obtain comfortable and objective measures of the timing of human retinal potentials while obtaining quantitative behavioral measures of both the observer’s state of attention and of visual performance. If the present prediction is confirmed by such measures, it would allow the mfERG technique to be used for both the objective diagnosis of and the quantitative evaluation of treatments for a variety of attention disorders. These would include attention deficit hyperactivity disorders as well as several psychoses that involve attentional difficulties. The costs of testing TBC are modest; the potential benefits of applying this neurocomputational technology to assist sufferers could be substantial.     

Distribution of enteric glia and GDNF during gut inflammation

Background  

The enteric glia network may be involved in the pathogenesis of inflammatory bowel disease (IBD). Enteric glia cells (EGCs) are the major source of glial-derived neurotrophic factor (GDNF), which regulates apoptosis of enterocytes. The aim of the study was to determine the distribution of EGCs and GDNF during gut inflammation and to elucidate a possible diminished enteric glia network in IBD.     

Measurement of parenting self-efficacy and outcome expectancy related to discussions about sex.

The purpose of this study was to evaluate the psychometric properties of two scales--one to measure the self-efficacy of parents to discuss sexual health issues with their adolescents and the other to measure parents' outcome expectancy associated with such discussions. Understanding how parents feel about their confidence in talking with their children about important sexual health issues and the outcomes they expect as a result of such discussions can be useful in guiding both the development and refinement of educational programs to promote parent-child discussions. The responses of 491 mothers who participated in an HIV prevention intervention with their adolescents were used for the present analysis. Mothers ranged in age from 25 to 68 years with a mean of 37.9 years (SD = 6.9). Of mother participants, 33% were married, 96.7% were African American, and 89.2% had completed high school. Their adolescents ranged in age from 11 to 14 years, and 61.5% were male. Assessment of reliability for both scales showed that internal consistency reliability was acceptable for the total scales as well as three of the five subscales. With the exception of one item on the outcome expectancy scale, the inter-item correlations, the mean inter-item correlations, and the item-to-total correlations meet the standard criteria for scale development for both scales. Factor analysis was used to identify the underlying structure of the scales, and hypothesis testing was used to assess construct validity. The results of these analyses provide support for the construct validity of the scales.     

Lack of adverse cognitive effects of 1 Hz and 20 Hz repetitive transcranial magnetic stimulation at 100% of motor threshold over left prefrontal cortex in depression.

OBJECTIVE: The potential therapeutic effects of repetative transcranial magnetic stimulation (rTMS) are being examined in various neuropsychiatric illnesses. This study assesses the cognitive performance of depressed patients receiving high or low frequency rTMS for 10 days. METHODS: 18 depressed patients participated in a randomized double-blind cross-over study exploring the antidepressant effects of 2 weeks (10 daily) of sham, 1 Hz, or 20 Hz rTMS administered over the left dorsolateral prefrontal cortex at 100% of motor threshold (MT). A subgroup completed a battery of cognitive tests at baseline and following each 2-week phase of treatment, and differences in performance were assessed using paired t -tests and were correlated with the degree of clinical improvement using Hamilton Depression Rating Scale scores. RESULTS: There were no major changes in cognitive test scores as a result of 10 days of either 1 Hz or 20 Hz rTMS. Moreover, any minor attenuations in cognition were not related to the degree of clinical improvement. CONCLUSIONS: Cognitive functioning in many domains following 2 weeks of 1 Hz or 20 Hz rTMS at 100% MT over the left dorsolateral prefrontal cortex in depressed patients is not disrupted.     

Reliability of normal findings on MR imaging for excluding the diagnosis of vasculitis of the central nervous system.

OBJECTIVE: We attempt to determine whether angiography is indicated in patients with suspected central nervous system (CNS) vasculitis who present with negative findings on MR imaging studies. CONCLUSION: MR imaging findings may be negative in the setting of CNS vasculitis confirmed on angiography, indicating that advanced imaging techniques tailored to detect infarction (i.e., fluid-attenuated inversion recovery, diffusion-weighted, and perfusion imaging) may be necessary to enhance the sensitivity of an MR study and that despite the high sensitivity of MR imaging for CNS vasculitis, angiography may still be required to render an accurate diagnosis.     

GeneLynx: a gene-centric portal to the human genome.

GeneLynx is a meta-database providing an extensive collection of hyperlinks to human gene-specific information in diverse databases available on the Internet. The GeneLynx project is based on the simple notion that given any gene-specific identifier (accession number, gene name, text, or sequence), scientists should be able to access a single location that provides a set of links to all the publicly available information pertinent to the specified human gene. GeneLynx was implemented as an extensible relational database with an intuitive and user-friendly Web interface. The data are automatically extracted from more than 40 external resources, using appropriate approaches to maximize coverage of the available data. Construction and curation of the system is mediated by a custom set of software tools. An indexing utility is provided to facilitate the establishment of hyperlinks in external databases. A unique feature of the GeneLynx system is a communal curation system for user-aided annotation. GeneLynx can be accessed freely at http://www.genelynx.org.